feat: pidproxy and Makefile

cmd/pidproxy/Makefile

@@ -0,0 +1,5 @@
+all:
+	go build -v
+
+clean:
+	go clean -i -cache -testcache

cmd/pidproxy/pidproxy.go

@@ -0,0 +1,134 @@
+package main
+
+import (
+	"log"
+	"os"
+	"os/exec"
+	"strconv"
+	"syscall"
+	"time"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	"golang.org/x/sys/unix"
+)
+
+const (
+	pidFileFlag = "pid-file"
+)
+
+var (
+	rootCmd = &cobra.Command{
+		Use:  "wmpidproxy",
+		RunE: pidProxy,
+	}
+
+	childArgs []string
+)
+
+func main() {
+	var (
+		i        int
+		arg      string
+		selfArgs []string
+		found    bool
+	)
+
+	if len(os.Args) <= 2 {
+		log.Println("invalid argument")
+		os.Exit(1)
+	}
+
+	rootCmd.PersistentFlags().StringP(pidFileFlag, "p", "", "location of pid file")
+	rootCmd.MarkFlagRequired(pidFileFlag)
+	viper.BindPFlag(pidFileFlag, rootCmd.PersistentFlags().Lookup(pidFileFlag))
+
+	found = false
+	for i, arg = range os.Args {
+		if arg == "--" {
+			found = true
+			selfArgs = os.Args[1:i]
+			if len(os.Args) <= i+1 {
+				log.Println("invalid argument")
+				os.Exit(1)
+			}
+			childArgs = os.Args[i+1:]
+			break
+		}
+	}
+	if !found {
+		log.Println("invalid argument")
+		os.Exit(1)
+	}
+
+	rootCmd.SetArgs(selfArgs)
+
+	if err := rootCmd.Execute(); err != nil {
+		log.Println(err)
+		os.Exit(1)
+	}
+}
+
+func pidProxy(cmd *cobra.Command, args []string) error {
+	pidfile := viper.GetString(pidFileFlag)
+	log.Printf("%s %v", pidfile, childArgs)
+	if len(childArgs) > 1 {
+		go startProcess(childArgs[0], childArgs[1:]...)
+	} else {
+		go startProcess(childArgs[0])
+	}
+	time.Sleep(time.Second)
+
+	var (
+		err error
+		pid int
+	)
+	for {
+		if pid, err = readPid(pidfile); err != nil {
+			return err
+		}
+
+		if err = unix.Kill(pid, syscall.Signal(0)); err != nil {
+			return err
+		}
+
+		time.Sleep(time.Second)
+	}
+}
+
+func readPid(pidFile string) (int, error) {
+	var (
+		file  *os.File
+		err   error
+		buf   []byte
+		n     int
+		pid64 int64
+	)
+
+	if file, err = os.Open(pidFile); err != nil {
+		return 0, err
+	}
+	defer func() {
+		_ = file.Close()
+	}()
+
+	buf = make([]byte, 1024)
+	n, err = file.Read(buf)
+	if err != nil {
+		return 0, err
+	}
+
+	pid64, err = strconv.ParseInt(string(buf[:n]), 10, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	return int(pid64), nil
+}
+
+func startProcess(arg0 string, args ...string) {
+	if err := exec.Command(arg0, args...).Run(); err != nil {
+		log.Println("exec:", err)
+		return
+	}
+}